NFDBITS
for (sock = 0; sock < FD_SETSIZE; sock += NFDBITS) {
fdmasks = howmany(s + 1, NFDBITS) * sizeof(fd_mask);
tmp = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask);
return (fd_set *)malloc(howmany(getdtablesize(), NFDBITS) * sizeof (fd_mask));
memset(s, '\0', howmany(getdtablesize(), NFDBITS) * sizeof (fd_mask));
fdsr = (fd_set *)calloc(howmany(fdsrmax+1, NFDBITS),
bzero(fdsr, howmany(fdsrmax+1, NFDBITS) *
fdsn = howmany(sock+1, NFDBITS) * sizeof(fd_mask);
fdsn = howmany(sock + 1, NFDBITS) * sizeof(fd_mask);